Mischievous sprite could make you lose your sight, virtually (6)
I believe the answer is:
goblin
'mischievous sprite' is the definition.
(I've seen this before)
'lose your sight virtually' is the wordplay.
'lose your sight' becomes 'go blind' (to go blind is to lose your sight).
'virtually' means to remove the last letter (all but the last letter).
'goblind' with its last letter taken off is 'GOBLIN'.
'could make you' is the link.
(Other definitions for goblin that I've seen before include "nasty little thing" , "Malevolent imp" , "Small grotesque supernatural creature" , "Evil imp" , "Naughty sprite" .)